<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0px;
        }
        .bnt{
            width: 100px;
            height: 30px;
            background-color: turquoise;
            border: 0px;
            color: white;
            float: left;
            flex-grow: 1;
            text-align: center;
            
        }
        .bnt:hover{
            background-color: aquamarine;
        }
        .bnt:hover .spean{
            padding-right: 10px;
        }
        .parent{
            width: 100%;
            height: 100%;
            display: flex;
            flex-direction: column;
        }
        .spean{
            line-height: 30px;
            transition: 1s;

        }
        .jiantou{
            display: inline;
            transition: 0.5s;

        }
    </style>
</head>
<body>
    <div class="parent">
        <div class="bnt">
            <spean>按钮</spean><spean class="jiantou">&lt;&lt;</spean>
        </div>
     
    </div>
</body>
</html>